Katy Perry and John Mayer over already: Who had the fastest celeb fling?

Blink and you missed 'em. Katy Perry and John Mayer are no longer dating, a source tells People. "They'll end up as friends," the source says. "They were honestly having fun. People made it out to be far more than it was."

Perry is still reeling from her short-lived marriage to Russell Brand, but another source told People that Perry, 27, and Mayer, 34, seemed happy together. "They almost acted like they've been a couple for a long time," the observer said. "It definitely didn't seem like a new relationship."

The Perry-Mayer sightings began in West Hollywood on June 19, meaning the romance lasted a solid two months -- not too bad by Hollywood standards! From Katy and John to Taylor Swift and Jake Gyllenhaal, let us know: Which celebs had the fastest fling?